Practical Alternative Microwave Technology to Enhance Recovery Heavy Oil in Reserviors

ABSTRACT

Extracting of Heavy Oil (Hydrocarbon) from Tar Sand and Oil Shale in deep reservoirs 7,000-12,000 feet below the ground surface by using Circular Waveguides Technology and Microwave Energy High Power System. Using Circular Waveguides as microwave energy radiator connects to the Microwave High Power System is the most practical method and provides a relatively cost-effective means of extract heavy oil from target Tar Sand or Oil Shale in deep reservoirs. This invention method can be applied for future new well bores that are in the plan to be drilled. It also can be used for existing un-use well bores that are being closed; waiting for cleaner new enhance oil recovery technology becoming available in order to reclaim of heavy oil without damaging the environment.

CROSS REFERENCES U.S. Patent Documents

U.S. Pat. No. 4,140,180 Feb. 20, 1979 Jack Bridges “Method For In SITU Heating Processing of Hyrocarbonaceous Formations”

U.S. Pat. No. 7,091,460 B2 Aug. 15, 2006 Dwight Eric Kinzer, “In SITU Processing of Hyrocarbon-Bearing Formations with Variable Frequency Automated Capacitive Radio Frequency Dielectric Heating”

U.S. Pat. No. 0,173,488 A1 Jul. 9, 2009 Ravi Varma, “High Power Microwave Petroleum Recovery”

U.S. Pat. No. 8,720,549 B2 May 13, 2014 Dwijen K. Barnerjee, “Process For Enhanced Production of Heavy Oil using Microwaves”

U.S. Pat. No. 0,289,736 A1 Dec. 20, 2007, Peter M. Kearl and Donald L. Ensley, “Microwave Process For Intrinsic Permeability Enhancement and Hydrocarbon Extraction From Subsurface Deposits”

US 2011/0114470 A1 May 19, 2011, Chang Yul Cha and Paul Gil Vergnani, “Process and System For Recovering Oil From Tar Sands Using Microwave Energy”

FIELD OF THE INVENTION

This invention relates to extraction of heavy oil recovery from tar sand or oil shale in well bores depth from 7,000-12,000 feet below the ground surface, and possibly can be used for deeper well beyond 12,000 feet deep. Circular Waveguides technology and Microwave High Power System are the equipment needed for the deep reservoirs, and capable to deliver adequate of RF power to melt thick viscosity of oil rapidly.

BACKGROUND OF INVENTION

1. Oil is a very important commodity and the demand of oil is on the rise all over the world. Crude oil is being produced from the light oil deposits which are only one third of all world oil reserves. The other two thirds belong to heavy and extra heavy crude oil group and only one percent is being exploited. With increasing process of crude oil, the increasing prices of crude oil, the production from the heavy and extra heavy oils will become more economically profitable and the scale of their exploitation will increase. There is estimating 65% of oil have not been recover yet and vast of oil are still in the existing well bores waiting to be recovered. Petroleum engineers are well aware of 65% oil is still in the well bores and tremendous amount of oil come from tar sand and oil shale have not recover. Because of well bore depths are too far below the ground surface, there is no one environment friendly method available to extract it or capable to deal with such of deep depths from 7,000-12,000 feet and beyond. Many deep wells are still un-touch because of the heavy oil viscosity in the range of 12 API-18 API or higher. Typically, heavy oil is very expensive to extract and the recovery is not as fast like the lighter viscosity oil. Conventional recovery extract methods are being used today such as steam injection, thermal injection well, gas injection, and chemical injection. Although these recovery methods are doable but they do creating contaminations and damaging the environment above and below the ground surfaces; this is one of the main reasons many existing well bores are capped for the time being.

2. In addition, in the US, the Environmental Protection Agencies (EPA) imposing tougher regulations on oil companies because they are afraid of oil destroy the environment. For example, the current recovery hot steam method leads to environmental problems with the improper disposing of toxic water and the releasing of CO₂ into the atmosphere. The main problem with the present extraction methods arise from the contamination of water bodies. There are already lagoons contaminated with the toxic waste from tar sand mining. Another problem is the transport of bitumen through pipelines due to tar sand viscosity; it is very difficult to transport bitumen like the conventional crude oil. In order to transport bitumen, it is mixed with conventional crude or chemical to decrease viscosity which enhances flow. Transported bitumen also contained impurities like sand and other waste which need to be removed at great cost. Therefore, oil producing operators are bound by the EPA regulations which restrained them from increasing in drilling and leave them no choice but to find other new environment friendly method in order to extract more heavy oil from production wells.

3. There are several patents proposal on enhance recovery of hydrocarbon or heavy oil by using microwave:

U.S. Pat. No. 0,289,736 describes microwave process for intrinsic permeability enhancement and hydrocarbon extraction from subsurface deposits. Apparatus are microwave klystron, water-cooled waveguide or coaxial cable connects to phase array antenna, and using phase array antenna as a radiation source to heat hydrocarbon. This is to enhanced intrinsic permeability of the region between the phase boundary and well allow specific targeting of hydrocarbon rich zone. This method is only be used for shallow extraction less than 500 feet depth. This method is mainly used for shallow depth and it is ineffective for the deeper wells. Another disadvantage is coaxial cable has very high propagation loss and a lot of RF transmission power lost for very deep well.

U.S. Pat. No. 8,720,549 describes process for enhanced production of heavy oil using microwave. Apparatus are electrical wire, waveguides, steam water injection, microwave injection, frequency heating device. This process is to flood heated water on to the heavy oil well bore and utilizing microwave at the same time heating the reservoir. Another problem with this method uses enormous water flooding with steamed water in to the well bore will contaminate the environment. Frequency heated device and microwave generating probe are unknown and too vague of description to make of it.

U.S. Pat. No. 0,173,488 describes methods, systems and devices are for using high power microwave radiation to recover oil from oil shale deposit. Using one or more antennae propagate the microwave radiation into the oil shale deposit. Apparatus are microwave generator, power cable, rectangular waveguide wr-340, and slotted antenna as a radiator. This method can be complicated because the microwave generator is below the ground surface and sitting inside the oil shale deposit. If something goes wrong with microwave generator, it will be very difficult to do repair. Another disadvantage is the rectangular waveguide has high attenuation loss and a lot of RF transmission power is lost for very deep well. This method is inefficient and insufficient for well bore depth greater than 7000 feet.

U.S. Pat. No. 7,091,460 describes In SITU Processing of Hyrocarbon-Bearing Formations with Variable Frequency Automated Capacitive Radio Frequency Dielectric Heating. Apparatus are coaxial cable, linear amplifier, computer controller, impedance matching, heated fluid injection. This process is to flood heated water on to the heavy oil well bore and utilizing microwave at the same time heating the reservoir. Another problem with this method uses enormous water flooding with steamed water in to the well bore will contaminate the environment. Another disadvantage is coaxial cable has very high propagation loss and a lot of RF transmission power lost for very deep well.

Despite all of the above patented methods presentations, some using parallel plates as RF radiator devices with water injection into the well bores to heat tar sand and shale oil. Some using antennas connect to coaxial cables or rectangular waveguides as RF radiators to heat heavy oil viscosity, and most of methods can only applied for shallow wells depth. Therefore, this invention offers an alternative enhanced method that provides more effective practical approach from electrical and mechanical perspectives how to heat the tar sand or shale oil more efficiently and rapidly. It provides more superior practical advantages over any radiator devices such as coaxial cables, rectangular waveguides, antennas and other hardware that are existing today. This invention offers very high reliability and it does design to accommodate for different types of well depths. The design could offer greater cost benefits and reduce field implementation cost.

SUMMARY OF INVENTION

Extraction of heavy oil recovery from tar sand or oil shale in well bores depth from 7,000-12,000 feet below the ground surface, and possibly can be used for deeper reservoirs.

Unlike existing recovery heavy oil methods mention in above patents, this invention does not use any additional water injection, steam injection or chemical injection into the wellbore nor any additional RF radiator attachment devices such as dipole antennas, phase array antennas and coaxial cables in order to heat tar sand and oil shale. In fact, it is design for a long term use, increases reliability and decreases maintenance in the long run by having less radiating devices or attachments. One unique about this invention is only required two pipes go into the ground that fit inside the Well Bore Hole Casing running down into the reservoir where the tar sand and oil shale deposits.

One of the challenges is to have a heating and recovering system that has the flexibility to fit through the Casing Borehole and reach to the desired depth of the well. Many of deep existing Casing Borehole openings are in the diameter range of 7-13 inches. These openings could put a stop on using big pipes bigger than 5 inches in diameters and the space is very limited to maneuver in 12,000 feet below the ground surface. The invention has the flexibility to use smaller diameter of microwave circular waveguide pipe fit into tight casing opening of 7 inch and higher to reach a desire depth. A recommendation for circular waveguide pipes inside diameter 2.90-3.50 inch.

Using Circular Waveguide open-ended radiator is capable of producing very strong radiation energies needed to heat tar sand and oil shale in deep reservoirs. This approach decreases the viscosity of the tar sand or oil shale in the absence of oxygen and causes trapped oil in the tar sand to flow much more quickly than current steam injection process. It also heat up the trapped water embedded in tar sand or oil shale very rapidly.

Circular Waveguide is the ideal technology hardware to be used in deep reservoirs. It offers the highest possible efficiency with attenuation up to 50% lower than corresponding rectangular waveguides and coaxial cables. The RF transmission is greatly better for very long distance, very high power handling capability and capable to deliver tremendous of radiation power into deep wells to heat the heavy oil viscosity in the vast tar sand and oil shale reservoirs. Circular waveguide allows to heat hydrocarbons directly by radiating at a target formation.

Above ground microwave high power system is designed to produce 1.5 megawatt or greater of RF power to speed up the heating process in vast reservoirs. The source cooling liquid or heat exchanger must be used to keep the Cross field or Klystron or Magnetron amplifier cool and maintain stability output power and cooling along with other microwave components used inside the system. The system is designed with proper protection any high RF power reflected waves coming back into the source and to keep the system running continuously for a very long duration. None of the liquid cooling should be used on the outside of microwave high power source facility.

Only two pipes are used for in each well bore casing: one Production Recovery Pipe and one Microwave Circular Waveguide attached in parallel formation assembly or lying side-by-side as they are going down into the well bore where tar sand or oil shale deposit is located. The assembly creates a good thermal conduction barrier that transfer heat from circular waveguide pipe to production recovery pipe and can be used proportionally along the pipes where is needed. Circular waveguide pipe has certain RF power transmission loss when RF power travelling along the circular waveguide pipe produces thermal heat and that heat can be used to keep the oil viscosity thin inside in the production pipe. The circular waveguide will be made in a certain length section as long as possible, the length of each waveguide section can be manufactured as specified by the pipe manufacturers.

This approach increases time to breakdown the hydrocarbon, decrease oil viscosity quicker, increase oil recovery production; reduce the research and development time and upfront implementation cost.

DESCRIPTION OF DRAWINGS

FIG. 1: Shows the invention illustrations of a circular waveguide pipe and a production recovery pipe inside of well borehole casing.

FIG. 2: Shows the enlarged view of circular waveguide pipe and production recovery pipe construction.

FIG. 3: Shows the construction of the circular waveguide pipe assembly.

DETAILED DESCRIPTION of FIGS. 1-3

It is understood that the frequency at 2.450 Gigahertz is where the water resonates and absorbs highest microwave radiation energy at microwave frequency spectrum; heating water to boiling temperature in order to break down heavy oil in reservoir. It is also understood that the tar sand and oil shale have certain permittivity and attenuation values at microwave frequency that significant enough to absorb microwave power heating up the hydrocarbon and breaking down heavy oil viscosity to lighter viscosity. This invention is focus on these ideas and developed a practical alternative microwave enhancement method for better recovery in heavy oil reservoirs from tar sand and oil shale in deep reservoirs, much cleaner and friendlier for earth environment.

FIG. 1 shows the front view invention illustration of a microwave circular waveguide pipe 1 and a production recovery pipe 2 inside of well borehole casing 5. Both pipes run from the above ground surface down into the reservoir 12,000 feet below where heavy oil deposit is located. There are several sizes of circular waveguide can be used for heavy oil application, however the invention is focusing on the largest inside diameter 3.50 inch because it has greatest efficiency in microwave. This 3.50 inch (4.45 cm) diameter pipe is chosen to operate in wide range of frequency 2.100-2.570 Gigahertz (GHz) and operates at 2.450 GHz. This hollow circular waveguide pipe 1 is defined by circular cross-section supports both Transverse Electric (TE11) and Transverse Magnetic (TM01) Waves. The circular waveguide 2 TE11 Cutoff

Frequency is 1.979 GHz dominant mode to lower-order propagating modes and TM01 Cutoff Frequency is 2.585 GHz is the next mode higher order. TE01 of interest for low loss transmission over long distance, it offers the highest possible efficiency with attenuation up to 50% lower than corresponding rectangular waveguides and coaxial cables existing today. TE01 is the first mode to propagate and the one mode is most frequent used in circular waveguide. For example, shows 3.50 inside diameter attenuation is estimated 19 dB at 2.450 GHz for 12,000 feet in length, and attenuation for 7,000 feet in length is estimated about 11 dB. These circular waveguide pipe 1 diameters are capable handling very high Continuous Wave (CW) Breakdown Power up to 20 Megawatt at 1 atmosphere, operating at frequency 2.450 GHz and in the frequency range of 2.10-3.10 GHz. It is far better than rectangular waveguide and coaxial cable for very long distance and certainly is good for microwave heating deep oil reservoirs applications. These diameters are chosen pipe is capable to handle most of the power coming from microwave source propagates RF waves down the pipe. At the end of the circular waveguide pipe 1 will be capped with special Microwave Dielectric Cap 7 material. The RF passing through the dielectric material radiates surrounding heavy oil. At the same time, it capable to handle very high pressure and prevent any moisture from coming into the pipe. The material can be made out of Alumina, Fused Quartz, Fused Silica or other ceramic materials that offer low loss tangent, allow high RF power to pass through, and capable to handle higher than the nominal operating temperature and pressure in deep reservoirs.

The hollow circular waveguide pipe 1 can be made out of copper, brass or aluminum metals. The circular waveguide pipe 1 make in an individual tubular section to a certain length for various inside diameters between 2.90-3.50 inch. The conductor loss for 2.90 diameter tubular is slightly higher than the 3.50 diameter by 11% at 2.45GHz. The outer diameter wall thickness of circular waveguide pipe 1 is designed to meet specifications as stated in the American Petroleum Institute (API) Tubing Standard. It is recommended that each tubing section to be manufactured in a long length section as possible or as long as the pipe manufacturers can produce it. At each at end of the circular waveguide pipe 1, a circular flange 3 with screw holes attached to the pipe tubing. One of the circular flanges is specially designed to accommodate RF gasket and to seal the moisture from coming inside the waveguide. For decrease the conductor loss at microwave frequencies, it is recommended to use Copper metal for better conductor loss. It has better conductivity then Aluminum and Brass and no need for Silver Plating inside the waveguide pipe surface and flange surfaces. For harsh environment application, Brass is a better metal to use for harsh conditions. To improve the conductor loss up to 40% at microwave frequencies, Silver Plating must be used inside circular waveguide pipe 1 surface and flange surfaces. For weight constraint application, Aluminum is a better metal to use. To improve the conductor loss up to 40% at microwave frequencies, Silver Plating should be used inside circular waveguide pipe 1 surface and flange surfaces. The outside wall for any of these metal circular waveguide pipe can be painted or should be treated with chemical to prevent corrosion in harsh environment.

The invention is using parallel piping method similar to the dual-zone completion using parallel tubing strings method (which does not shown here). Although the invention uses similar approach but there is one big different between the two is that this invention uses microwave circular waveguide pipe 1 as a heating component for heating heavy oil from tar sand or oil shale in deep reservoirs. The circular waveguide pipe 1 has one function is to produce rapid microwave heating only supplied by the microwave high power system 9; it does not collecting oil or fluid like the production recovery pipe 2. In most applications where the microwave circular waveguide pipe 1 and production recovery pipe 2 needs to be side-by-side to each other. It is recommended one dual packer 6 per casing should be used to protect the casing from blow out and to keep the cost down. Another big advantage is by using microwave circular waveguide pipe 1 can easily retrofitted and embedded within the dual packer 6. This does not require any special design and development works for new packers. By using existing dual packers available in the market, this would benefits in several areas such as speed up the implementation time, there is no new design and development efforts put into the packer 6. This is a huge cost saving benefit.

Any standard Temperature and Pressure sensors 8 can be used for this invention. These monitoring sensors are very helpful providing reliable downhole data continuously monitored the temperature and pressure conditions in deep reservoirs. It is recommended as an optional feature for effective reservoir surveillance.

The Thermal Clamp 4 can be used and implemented in two ways: one way is to use as a heat transfer device and can be made out of the same or compatible metal material as circular waveguide pipe. As mentioned above, microwave circular waveguide pipe 1 produces heat as RF power traveling down the pipe. This heat can be transferred on to production recovery pipe 2 to keep the oil viscosity thin on the inside. The thermal clamp 4 can be placed along the tubular down to just above the dual packer 6, and below the packer 6 if needed. Fins can be added to thermal clamp will greatly improve heat conduction and heat dissipation between two pipes. Second way is to use the thermal clamp as a mechanical damp to hold the pipes together, keeping the pipes from extreme pipe movement, stresses on pipe and high axial packer-to-tubing forces might encountered in high pressure and high temperature well completions. It is very important and highly recommended to use the thermal clam to keep microwave circular waveguide pipe 1 to be in a straight line as possible for long distance pipe run. Any bends, dents and kinks on the inside of the pipe will tremendous effect the microwave power transmitting down to the reservoir, cause RF Voltage Standing Ratio (VSWR) to go up, a lot of RF power being reflect back to the source and potentially could damage the microwave high power source 9. It is important to keep VSWR low as possible for very long distance run.

A microwave high power source 9 should provide high RF Continuous Wave (CW) power in the greater than 1.5 megawatt. The three sources are capable to produce power in the megawatts typically the Crossed Field Amplifier, Klystron Amplifier and Magnetron Amplifier that operate in the frequency range of 2.10-3.10 GHz with the efficiency between 10-30%; preferably the sources efficiency close to 60%. Having extra CW power capacity is important to compensate for the conductor losses were not accounted for especially at higher frequency range and for longer pipe run. It is important that the RF power output port must be a circular waveguide and circular flange that connect to external circular waveguide pipe 1. These three super power sources are commercially available and have been use in microwave radar applications, and certainly can be applied to oil industry to heat heavy oil from tar sand and oil shale.

Above ground surface microwave high power source 9 should be design with high reliability and stability to sustain for very long duration of usage. Cooling liquid or heat exchanger should be used inside of the microwave high power system to keep the Cross field or Klystron or Magnetron amplifier cool and stable along with other microwave components used inside the system. None of the liquid cooling should be used on the outside of microwave high power source 9. The amplifier source must be protected from any high power reflected waves coming back into the microwave source 9. Reflected waves created are usually coming from arcing problem and high VSWR. When arcing occur due to very high potential of voltage anywhere along the circular waveguide pipe 1, it sends tremendous of reflected power waves back to the microwave source 9. High VSWR occurs due to impedance mismatch along the circular waveguide pipe, it constantly sending reflected power waves back to the microwave source 9. It is recommended strategically placed an arcing detector inside the waveguide between the amplifier output port and the circular waveguide pipe 1 and where most vulnerable area to damage the amplifier source and shut down the system as soon as detector detects surge of RF power being reflected. These protection microwave components should be used to protect the source such as arcing detectors, circulators, isolators and loads.

Above ground microwave high power source 9 should have a power management system manages the operations of input power and output power microwave radiation. The management system should be able to increase or decrease levels of radiating power to melt the heavy oil from tar sand and oil shale in the reservoir.

FIG. 2 shows the front and bottom views enlarged view of circular waveguide pipe 1 and production recovery pipe 2 assembled together inside the borehole casing. The circular waveguide pipe 1 can be offset in length to reach desire depth closer to the tar sand or oil shale.

FIG. 3: Shows the front view construction of the circular waveguide pipe 1 assembly. The waveguide assembly can be made out of Cooper, Brass and Aluminum tubing and the flanges 3 are also made from the same metals. Because brass and aluminum have poorer conductivity, it is important to use silver plating inside the pipe and on flange surfaces to improve conductor loss and provide a good contact between flanges. Table 1 shows conductivity of different metals.

TABLE 1 Conductivity of Different Metals Metal Material Conductivity (S/m) Aluminum 3.816 × 10⁷ Brass 2.564 × 10⁷ Copper 5.813 × 10⁷ Stainless Steel 1.100 × 10⁶ Silver 6.173 × 10⁷ 

1. A practical alternative method for extraction of heavy oil recovery from tar sand or oil shale in the well bores depth from 7,000 -12,000 feet below the ground surface, and possibly can be used for deeper reservoirs.
 2. Circular Waveguide Pipe is an ideal technology hardware to use in deep reservoirs. Circular Waveguide gives more mechanical advantages in design and development time, ease of hardware interchangeability and compatibility, reduces replacement time and maintainability costs.
 3. The method in claim 2 where Circular Waveguide pipe inside diameter 3.50 inch (4.45 cm) operates at 2.45GHz and in frequency range of 2.100-2.570 Gigahertz (GHz). Smaller Circular Waveguide pipe diameters in between 2.90-3.30 inch are usable and operate in the frequency range of 2.2-3.1 GHz.
 4. The method in claim 2 where Circular Waveguide pipes is the best technology for long distance run because it has the lowest electrical attenuation loss and capable handling far more Continuous Wave power than corresponding rectangular waveguides and coaxial cables.
 5. The method in claim 1 where Practical Alternative Microwave Technology method is much cleaner and safer to the environment in deep wellbores. Alternative enhanced method uses much smaller compacted circular radiating device over other existing methods. Unlike the other methods, this alternative enhanced method does not require any additional water injection, steam injection or chemical injection into the wellbore nor any additional RF radiator attachment devices such as dipole antennas, phase array antennas and coaxial cables in order to heat the tar sand and oil shale.
 6. The method in claim 2 method has flexibility to accommodate many existing deep casing boreholes smaller than 7 inch diameter.
 7. The method in claim 2 method where equipment uses for the invention is compatible with industry standard requirements, which will result in huge cost savings.
 8. The method in claim 1 & claim 2 methods is to design circular waveguide Microwave Dielectric Cap out with special material capable to handle very high continuous wave microwave power and allows microwave passing through the dielectric material to radiates the surrounding heavy oil. At the same time, its capable to handle deep reservoirs high pressure and high temperature, and prevent any moisture from leaking into the circular waveguide pipe. 